Equipment for determining the geometric condition of a track and controlling the slew or lift thereof



Apnl 30, 1968 A. FORNEROD 3,380,394

EQUIPMENT FOR DETERMINING THE GEOMETHIC CONDITION OF A TRACK AND CONTROLLING THE SLEW OR LIFT THEREOF Filed Aug. 26. 1966 5 Sheets-Sheet l (Bk 11 i g= E J Ly. :J (A

Apnl 30, 1968 FORNEROD 3,380,394

EQUUNENT FOR DETERMINING THE GEOMETHIC CONDITION OF A TRACK AND CONTROLLING THE SLEW OR LIFT THEREOF Filed Aug. 26. 1966 5 Sheets-Shem Apnl 30, 1968 A. FORNEROD 6,380,394

I'IQUIIMUNT IOH Mn'lilHMlNLNU 'I'Hii UEOMIJJI'RIC UONDlTlON 01" A TRACK AND CONTROLLING THE SLEW OR LIFT THEREOF Filed Aug. 26. 1966 S Sheets-Sheet 3 SOL. I SERVO 0 L United States Patent O ABSTRACT OF THE DISCLOSURE Equipment for measuring and recording the geometric condition of a railroad track as well as for controlling the slew or lift of a track section. The invention incorporates means capable of being coupled with a measuring bridge arrangement, during which time the force applying means for displacing the track section undergoing checking is rendered inoperable, in order to adjust the starting position for the track displacement by balancing the comparison signal of the measuring bridge arrangement with the actual momentary position of the track section which is being checked. Further means cooperate with the measuring bridge arrangement for adjusting for a desired displacement of the track section. The track section is then shifted by the pre-set desired displacement so that the measuring bridge arrangement is again balanced.

The present invention has reference to improved apparatus or equipment for measuring and recording the geometric condition of .a railroad track as well as for controlling the slew or lift of a track section.

Automatic control devices are being employed in ever increasing degree with the mechanized work for lining or slewing and levelling of railroad tracks. The reference or desired position of the track is represented by a reference system in the form of a tensioned wire or a system of tensioned wires, or in the form of a bundle of light rays, or infrared rays. A feeler member which, for instance, can comprise a movable impact member, a feeler roller, a photoelectric cell and so forth, records the actual position of the railroad track in relation to the aforementioned reference system and determines the displacement path during lifting or shifting of the track which is brought about by a so-called force system.

Such equipment or apparatuses have in common the feature that the error signal for the automatic control of the displacement path is removed between the track and the reference system. During the course of displacement, the previous position of the track is eradicated, and the control is independent of the effective displacement distance. This does not have any importance if one is concerned with aligning the track in a geometric form or configuration fixed or determined by the reference system.

However, difliculties do occur if the situation requires that the track be displaced through a predetermined or prescribed path. One is forced to manually control the lifting or slewing cylinder while observing the track displacements with the aid of a sighting mechanism or the like placed upon the track. However, such sighting operation is time-consuming, and the measurements and track displacements are not accurate enough.

Accordingly, it is a primary object of the present invention to provide an improved apparatus of the mentioned type which overcomes the aforementioned drawbacks of the prior art structures.

Another, more specific object of the present invention relates to the provision of improved equipment for measuring and recording the geometric condition of a railroad track as well as for controlling the slew and lift of a track section in an extremely simple, highly accurate and reliable manner, without requiring any time-consuming sighting operation.

Still a further considerable object of the present invention has reference to an improved apparatus for measuring the geometric condition of a railroad track and for controlling the slew and lift of a track section in an extremely quick and reliable manner, while automatically bringing about a highly precise track displacement.

Yet a further object of this invention relates to improved equipment for measuring the geometric condition of a railroad track and for controlling the slew and lift of a track section, such apparatus or equipment being relatively simple and robust in construction, extremely reliable in operation, and relatively uncomplicated to use.

A further noteworthy object of the present invention has reference to improved equipment for measuring and, if desired, recording the geometric condition of a railroad track and for controlling the slew and lift of a track section, as well as enabling automatic displacement of the track through a prescribed distance or path by virtue of having previously recorded the geometric condition of the track.

Broadly speaking, the inventive apparatus for sensing the geometric condition of lengths of railroad track and displacing the same, when necessary, to desired position, comprises the combination of, means for sensing a variation in a predetermined geometric condition along the length of railroad track and producing at least two electrical signals of differing characteristics related to the variation in geometric condition; comparison means for receiving said two electrical signals and for developing an output sign-a1 from said two electrical signals representative of the direction and magnitude of the variation in geometric condition, and means responsive to said output signal for displacing the track to desired position.

More specifically, according to a preferred embodiment of inventive apparatus for measuring and recording the geometric condition of a railroad track as well as for controlling the lateral and elevational displacement of a track section, there is provided a force applying means or force apparatus which includes a hydraulic piston and cylinder drive means for acting upon and influencing the position of the track section which is being checked, movable feeler means for determining the position of such track section, measuring transducer means for converting the linear displacement of said movable feeler means into electrical signals, the strength of which is dependent upon the position of said movable feeler means. Additionally, a measuring bridge arrangement for comparing the electrical signals is provided, as is also a hydraulic servo valve means including a relay having a relay coil and a core for operating the piston and cylinder drive means of the aforesaid force apparatus, the position of the core of the relay coil being dependent upon the electrical comparison signal appearing at the output side of the measuring bridge arrangement. The aforesaid measuring transducer means incorporates output means which are connected to the end terminals of two measuring resistors of the measuring bridge arrangement. Further, a fixed control tap and a silding contact are provided for each such measuring resistor, and a manually operable adjustment mechanism is mechanically coupled with such sliding contact of one of said two measuring resistors, with indicator means being provided for indicating the position of said lastmentioned sliding contact. Additionally, an electrical adjustment mechanism is provided and with which the other of said sliding contacts is connected, the operation of said electrical adjustment mechanism being dependent upon the comparison signal delivered by said measuring bridge arrangement. Switching means enable selective tapping off of the comparison signal between said two measuring resistors either at said fixed center taps or at said sliding contacts, whereas further switch means selectively conduct said comparison signal to either said electrical adjustment mechanism for the aforesaid other sliding contact or to said relay coil of said hydraulic servo-valve.

Furthermore, the equipment designed according to the teachings of the present invention can, without difficulty--and which in itself provides a considerable advantagebe modified through the provision of a positional indicator for the aforesaid other of said sliding contacts of the second measuring resistance provided with the electrical adjustment mechanism, or through a continuously operating recording apparatus for plotting the position of the sliding contact. As will be apparent from the detailed description to follow, the position of this other sliding contact of the second measuring resistance is in direct correlation to the position of the track. The

thus modified or amplified equipment, therefore, enables the geometric condition of the track to be measured very easily and in uncomplicated manner.

The invention will be better understood, and objects other than those set forth above, will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIGURE 1 schematically illustrates an overall view, taken from the side of the inventive apparatus or equipment;

FIGURE 2 is a top plan view of the equipment depicted in FIGURE 1;

FIGURE 3 is a front view of the so-called force apparatus as viewed along the line 3-3 of FIGURE 4;

FIGURE 4 is a fragmentary top plan view of the aforesaid force apparatus;

FIGURE 5 is a front view of a portion of the reference system as viewed along the lines 5-5 of FIGURE 6;

FIGURE 6 is a fragmentary top plan view of the reference system; and

FIGURE 7 is a schematic circuit diagram of the apparatus or equipment of the present invention.

Describing now the drawings, and, in particular, referrin to FIGURE 1, it will be understood that the track T which is to be aligned is represented by the rails 1 and 2, of which the rail 1 forms the pilot or guide rail string, and further by the cross-ties or sleepers 3. The hereinafter to be described components which form the reference system R for the control of the displacement, the force applying members or force system F for the displacement of the trackwork, as well as the associated control elements, are operatively coupled with a self-propelling rail vehicle 4 which moves or travels upon the track T which is to be aligned. The direction of movement is conveniently indicated by the arrow 5. The rail vehicle 4 which is supported by two wheel axles 6 is considered to be sufiiciently heavy so that the track T is not displaced by the reaction forces which act upon the rails 1, 2 via the vehicle 4 and the wheel axles 6.

The lateral displacement or slewing is undertaken by means of a so-called force apparatus or force applying means F mounted at the front of the vehicle 4. This unit or apparatus protrudes sufficiently past the wheel axle 6 in order to positively provide a sufficient spacing between the slewing or lining location 7 and the nearest situated wheel axle 6.

This force apparatus or force applying means F is schematically depicted in FIGURES 3 and 4. It incorporates supports 8 fixedly connected with the frame structure of the rail vehicle 4 and carrying a shaft member 9 rotatable about an axis extending transverse to the track or trackwork T. Two arms 10 are fixedly connected with this shaft member 9. As a result, these arms 10 rotate conjointly about a horizontal axis. The weight of the 4 forward portion of the force apparatus F is supported via two rolls or rollers 11 upon the rails 1 and 2.

One of these arms 10 is hingedly connected with a hydraulic jack, namely a piston and cylinder drive means 12, the other arm with a rod member 13. The jack drive 12 and the rod member 13 are articulated with a rigid transverse beam 14 preferably formed of welded steel sections. At the end of this beam 14 there are located the rail tongs 100, each of which consists of a fixed inner impact member or jaw 15 and a pivotable outer impact member or jaw 16 which can be swung open. Both of these outer impact members 16 are actuated by means of the associated piston and cylinder drive means 17 wh ch are pivotably mounted at the columns 18 rigidly connected with the transverse beam 14.

The displacement or slewing force is brought to bear upon one of both string of rails, in this case upon the rail string 2. As such, the outer impact member 16 at the side of this rail string 2 is lowered, whereas the corresponding impact member or jaw 16 at the other rail string 1 is pivoted up or opened. In order to be able to displace the track T towards the right of FIGURES 3 and 4, the piston and cylinder drive means 12 must be extended. On the other hand, for displacement of the track T towards the left this piston and cylinder drive 12 is shortened.

Control of the displacement movement is in accordance with a reference system R which travels along with the vehicle 4. Actually, this reference system, as such, does not form part of the present invention, inasmuch as it has been described and claimed in the commonly assigned, co-pending United States application, Ser. No. 475,113 filed on May 19, 1965. Therefore, only enough of its physical structure will be described and shown herein as considered necessary for understanding the subject matter of the present invention, especially since reference may readily be had to the aforementioned co-pending application. Accordingly, this reference system R which has best been depicted in FIGURES 2, 5 and 6, encompasses two elements 20 and 21 (FIGURES 2) which, with the aid of tensioned wires 22, are constructed as a frame unit which retains its shape. Each of these elements 20, 21 is equipped with four feelers, here in the form of rollers 23, 24, 25 and 26, of which the rollers at the side of the guide rail string 1 are pressed against the head of such rail string by means of piston and cylinder drive means 19. These feeler rollers 23 to 26 are supported by transverse carriers 27, 27", 27" and 2 which provide fixed components of the elements 20 and 21. Both of the outermost transverse carriers 27' and 27" bear upon independent traveling axle means 28, whereas both of the intermediately disposed transverse carriers 27" and 27" located at the frame unit of the vehicle 4 are suspended at suitable slide rods.

The elements 20 and 21 are retained spaced from one another through their suspension at the frame of the vehicle 4, which suspension or mounting, however, simultaneously permits a rotation about a vertical axis and a transverse displacement of the carriers 27" and 27.

Two cables or wires 33 are fixed to the transverse carrier 27 near its ends. They are crossed beneath the frame of the vehicle 4 and their other ends are connected to a control lever means 34. The latter is mounted for rotation upon the transverse carrier 27" so as to be able to carry out rotational movement about a vertical axis. Rotation of the control lever 34 is transmitted through the intermediary of a sleeve or tube 36 to a finger 35. The tube 36 is guided in a hollow sleeve 37 which is fixedly connected with the transverse carrier 27". A movable feeler pin or finger 38, which is connected with the core 51 of an electric transducer or so-called measuring transducer means 50 e.g. a measuring transformer, the housing 161 of which is fixedly mounted at the transverse carrier 27", is continuously pressed through the action of spring force against the free end of the finger 35. Naturally, such transducer means 5 may also be a capacitive or resistance signal transmitter means.

With a completely linear track the feelers 23 to 26 at the side of the guide rail string 1 are aligned in a straight line. The control lever 34 and the finger 35 operably connected with such assume an exact predetermined position with respect to the transverse carrier 27". This relative position of the finger 35 is the same When the equipment is located at an are or curve. Each deviation of the location of the guide rail string 1 from an arc or from a straight line-limiting case of an arc-results in a relative rotation of the control lever 34 with respect to the transverse carrier 27". This mutual rotation of both components brings about a linear displacement of the feeler pin 38 and, therefore, also the core 51 with respect to the housing 101 of the measuring transducer 50. This displacement is proportional to the transverse displacement of the feeler 24 at the lining or slewing location 7. In this manner the measuring transducer indicates, in the form of electrical signals, the position of the track at this location with respect to the arc determined by the three other feelers bearing against the string of rails 1.

The electric measuring transducer 50, in the exemplary situation may be of the known type of differential transformer means which responds to the linear displacement of the core 51 (FIGURE 7). Its primary 102 is fed with a schematically indicated source of alternating current 103 having a predetermined amplitude and frequency. The secondary 104 possesses two identical induction coils 105 and 106. If the core 51 is located in the symmetrical position with respect to both secondary coils 105 and 106, these then generate two electrical signals of the same amplitude, yet directly opposite in phase, that is preferably 180 out of phase. If the core 51 is displaced then both of the signals also differ in amplitude, so that both signals can be compared in a measuring or comparison bridge arrangement M similar to a Wheatstone type measuring bridge.

In a practical embodiment of the present invention, as such has been shown by way of example in the circuit diagram of FIGURE 7, the signals delivered by the measuring transducer 50 are amplified in the amplifier means 52 having, as shown, a separate input and output for each signal, and are rectified in the rectifier means 53, likewise having a separate input and output for each signal. These signals are then delivered to the terminals of both measuring resistors 54 and 55 which are coupled in the measurement bridge circuit M. Each measuring resistor 54 and 55 has a fixed center tap 56 and 57 respectively, and a sliding contact or tap 58 and 59 respectively. The sliding contact or tap 58 is manually adjusted by means of the knurled screw 60. Its position is indicated at a gauge 60 having a scale 60a divided in millimeters for instance. The sliding contact 59 is mechanically adjusted by means of an electric regulating motor 61. The position of this sliding contact 59 is likewise indicated at a gauge 62 also having a scale 62a divided in millimeters. The scales 60a and 62a of the gauges 60 and 62 respectively, are calibratedin direct relationship with the movement of the feeler finger 38 with respect to the housing 101 of the measuring transducer means 50.

With the aid of the switch means 67 and 68 it is possible to selectively connect an amplifier means 63 either with the two fixed center caps 56, 57, or with both sliding contacts 58 and 59 of each measuring resistor 54 and 55 respectively, or with the fixed center ta-p of one measuring resistor and with the sliding contact of the other measuring resistor. The electrical output or comparison signal amplified in the amplifier 63, depending upon the position of the switch means 69, either feeds to a suitable regulating motor 61 or to a relay means 64 having a relay coil and core, generally designated 64a, of a hydraulic servo distributor or servo-valve 65. The position of the spring-biased valve spool 66 of the servo-valve 65 is dependent upon the polarity and the amplitude of the signals delivered to the relay coil 64a. The absence of a signal corresponds to a central position of the valve spool 66. The hydraulic servo distributor or servo-valve 65, in turn, controls the operation of the piston and cylinder drive means 12 in that, it analogously connects one cylinder chamber with the oil pump and the other cylinder chamber with the discharge. This servo-valve 65 is a combined electrical-hydraulic control unit which is readily available on the market. Its mode of operation is therefore well known to those skilled in the art, so that no further description thereof would appear to be warranted.

With the position of the switch means 67, 68, 69 shown in the circuit diagram of FIGURE 7, the electric output or comparison signal is tapped off between the fixed center taps 56 and 57 of both measuring resistors 54 and 55 respectively. The output side of the amplifier 63 is coupled with the relay coil 64a of the relay means 64. If the feeler members 23 to 26 of the string of guide rails 1 are exactly aligned in a straight line or are disposed at an are, then, as already mentioned, the core 51 of the measuring transducer 50 is in its central position. In this case, the comparison signal between both of the fixed center taps 56 and 57 disappears, that is, is zero. Therefore, the valve spool 66 of the servo-valve 65 remains in its central or neutral position under the action of the springs 66a, in which the delivery and discharge conduits for both cylinder chambers of the drive means 12 are closed.

Now, if the feeler 24 assumes a position which deviates from the arc determined by the three other feelers 23, 25 and 26, then the feeler finger 38 displaces the core 51 of the measuring transducer 50. Consequently, there appears an electrical comparison signal between the fixed center taps 56 and 57, the polarity and amplitude of which correspond to the direction and magnitude of displacement of the core 51 with respect to the housing 101 of the measuring transducer 50. This signal delivered to the relay coil 64a of the relay means 64 displaces the valve spool 66 of the servo-valve 65 out of its central or neutral position in the direction determined by the polarity of the signal. The servo-valve 65 places both of the cylinder chambers of the drive means 12 into communication with the oil delivery or with the discharge, depending upon the function to be carried out. The direction of displacement and the speed of displacement of the drive means 12 are dependent upon the direction and magnitude of displacement of the valve spool 66 with regard to the housing of the servo-valve 65. The track T is displaced and with it also the feeler finger 38 which is connected with the core 51 of the measuring transducer 50. When the track section is located at the proper place, then the core 51 of the measuring transducer 50 is again in its central position in which the electrical comparison signal between both fixed center taps 56 and 57 of both measuring resistors 54 and 55 respectively, disappears or becomes zero.

The switch means 67 enables the electrical comparison signal to be tapped off between the fixed center tap 57 and the sliding contact 58, instead of between the fixed center tap 57 and the fixed center tap 56. In this manner it is possible to intentionally act upon the comparison signal in order to have such disappear with a predetermined position of the feeler 24. This is of particular importance with curved track crossings.

Now, if it is desired to automatically displace the track through a predetermined path by virtue of having recorded the geometric condition of the track, something which was not possible with the previously known equipment, then one proceeds in the manner to be described hereinafter by combining the previously described working operations.

Specifically, initially the switch means 67 is placed in position I and the switch means 68 and 69 in position II. At the moment of placing the control apparatus into operation the regulating motor 61 is supplied with current under the action of the electrical comparison signal until such time as the sliding contact 59, driven by this regulating motor 61, has assumed that position in which the comparison signal between the sliding contact 59 and the fixed central tap 56 has disappeared or become zero. This automatic postioning of the sliding contact 59 determines the starting position for the track displacement.

Now, the sliding contact 58 is displaced in that, the indicator 60b of the gauge 60 is set to the marking of the scale 69a thereon which corresponds to the desired direction and the desired degree of track displacement. Then the switch means 67 is brought into position 11 and the switch means 69 into position I. In this position the relay coil 64a of the relay means 64 of the hydraulic servovalve 65 is supplied by the electric output or comparison signal which exists between both sliding contacts 58 and 59 of both measuring resistors 54 and 55, respectively. The displacement drive means 12 changes its length, as previously considered, and thereby displaces the track T in the desired direction for such time until the core 51 of the measuring transducer 50 is located in a position in which the mentioned signal between both sliding contacts 58 and 59 has returned to null. The valve spool 66 of the servo-valve 65 returns back into its central position and the displacement drive means 12 no longer moves. The path through which the track T has been displaced then corresponds to the value set at the gauge 64).

The displacement of the track through a predetermined path therefore takes place in two successive operations, each of which is triggered by actuating a switch means, yet which, however, proceed automatically. The first working operation entails the automatic adjustment of the sliding contact 59 by balancing the comparison signal of the measuring bridge arrangement with the actual position of the track. At the same time the displacement path is adjusted or set at the gauge 69'. The second working operation then resides in the automatic displacement of the track T through a path or distance set at the gauge 60.

On the other hand, it is also possible to transmit or transfer the position of the sliding contact 59 to a recording pen 70 or equivalent structure, which is moved simultaneously with the indicator 62b of the gauge 62 by the regulating motor 61. In this manner, there is obtained a plotting or recording of the geometric condition of the track at a recording chart 71, the course of which is a function of the path through which the rail vehicle 4 has moved. The direction and magnitude of displacement can then be read off the recording chart 71.

When carrying out this work in a practical manner it is possible, for instance, to travel over the same section of track twice with the rail vehicle 4. During the first passage the geometric track errors are plotted. Then the track locations which are to be corrected are indicated at the recording chart '71 and the vehicle 4, during its second pass, is stopped at such locations where then the plotted or indicated track errors are corrected.

The plotting or recordation of the gometrio track errors can likewise be obtained by direct plotting of the signals delivered from the measuring transducer 50.

The described embodiment relates to the displacement and slewing or lining in a horizontal direction transverse to the track. Naturally, it is possible to also proceed in the same manner for levelling the track. The geometric reference system is selected in accordance with different starting conditions, without it being necessary to modify the circuit arrangement of FIGURE 7. On the other hand, such circuit arrangement can be subjected to appropriate modification, which can be easily developed by those persons skilled in this particular art. Also, it would be possible to install further control and monitoring instruments in the electric circuit arrangement for functions which have nothing to do with the objects of the present invention.

The first of the two mentioned working operations can, for itself, serve for the determination of the geometric condition of the track in order to arrive at the required displacements. In this respect, it is suflicient, after stopping the regulating motor 61, to read the position of the sliding contact 59 at the gauge 62 or at the recording chart 71. If the indicator 62b of the gauge 62 has remained in the null position and if the equipment has been properly adjusted when it is placed into operation, then, from this, there can be deduced that the track exactly positioned along a straight line, or is aligned at an are determined by the three other feelers. On the other hand, the position of the indicator indicates the path or distance from which the track is removed from the reference or desired position.

The transducer or measuring transformer 50 with inductive signal transmitter can, as already mentioned, also be replaced by a transducer with capacitive or with resistance signal transmitter means having a direct currentvoltage supply. Such instruments are well known to those skilled in the electrical art and the acccornmodation thereof to the circuit arrangement of FIGURE 7 at the selected type of apparatus does not present any great ditliculties for the initiated, so that a further description of variants of this circuit arrangement would appear to be unneces sary. In the aforementioned instance where there is employed a resistance signal transmitter it would be possible to compare the signals delivered by the measuring transducer directly at a Wheatstone bridge.

It should be apparent from the foregoing detailed description, that the objects set forth at the outset of the specification have been successfully achieved. Accords v What is claimed is:

1. In an apparatus for measuring the geometric condition of a railroad track as well as for controlling the displacement of a track section, the combination of:

feeler means for sensing the position of a track section being checked,

force applying means for displacing the track section undergoing the checking operation,

control means for controlling operation of said force applying means,

an electrical circuit means responsive to the operation of said feeler means for selectively activating said control means,

said electrical circuit means including measuring transducer means for generating electrical signals as a function of the sensing operation of said feeler means, a measuring bridge arrangement operably coupled with said measuring transducer means for comparing the electrical signals received therefrom, and upon imbalance of said measuring bridge arrangement the latter delivers a comparison signal, first means capable of being selectively coupled with said measuring bridge arrangement, with said force applying means for displacing the track section rendered inoperable, in order to adjust the starting position for the track displacement by balancing the comparison signal of the measuring bridge arrangement with the actual momentary position of the track section being checked, and second means cooperating with said measuring bridge arrangement for adjusting for the desired displacement of said track section,

and switch means for selectively electrically operably coupling said measuring bridge arrangement with either said first means for operating the latter to carry out said balancing of said comparison signal with said actual momentary position of said track section or for electrically operably coupling said measuring bridge arrangement with said control means for operating the latter in response to said comparison signal delivered from said measuring bridge arrangement.

2. The apparatus defined in claim 1, wherein said measuring transducer means is a differential transformer, a source of alternating-current voltage for said differential transformer, said electrical circuit means further including amplifier means and rectifier means for respectively amplifying and rectifying said electrical signals generated by said measuring transducer means.

3. The apparatus defined in claim 1, wherein said measuring bridge arrangement incorporates at least two measuring resistors, each measuring resistor being provided with a fixed center tap and a sliding contact, said second means incorporating a manually operable adjustment mechanism mechanically coupled with said sliding contact of one of said two measuring resistors, said first means incorporating an electrically operable adjustment mechanism coupled with the sliding contact of the other of said measuring resistors, said switch means including a respective switch member for each measuring resistor selectively movable into one of two positions, one switch position placing said switch member in circuit with said fixed center tap and the other posi ion placing said switch member in circuit with said sliding contact of the associated measuring resisior.

4. The apparatus as defined in claim 3, wherein said switch means further includes a switching element for selectively feeding said comparison signal either to said control means or to said electrical adjustment mechanism.

5. The apparatus defined in claim 4, wherein said manually operable adjustment mechanism includes a gauge means for setting the amount which the track section is to be displaced.

6. The apparatus defined in claim 4, wherein said electrically operable adjustment mechanism includes a gauge means for indicating the degree of displacement of the sliding contact of said other measuring resistor necessary to automatically balance said measuring bridge arrangement so that there appears no comparison signal.

7. The apparatus defined in claim 6, further including recording means operated by said electrical adjustment mechanism for automatically plotting the direction and amount of displacement required of said track section.

8. Apparatus for measuring and recording the geometric condition of a railroad track as well as for controlling the lateral and elevational displacement of a track section, comprising a force apparatus including a hydraulic piston and cylinder drive means for influencing the position of the track section which is being checked, movable feeler means for determining the position of said track section, measuring transducer means for converting the displacement of said movable feeler means into electrical signals, the strength of which is dependent upon the position of said movable feeler means, a measuring bridge arrangement provided with at least two measuring resistors for comparing said electrical signals, servo-valve means including relay means for operating said piston and cylinder drive means of said force apparatus, the operation of said relay means being dependent upon the electrical comparison signal appearing at the output side of said measuring bridge arrangement, said measuring transducer means including output means which are connected to the end terminals of said two measuring resistors of said measuring bridge arrangement, a fixed center tap and a sliding contact provided for each measuring resistor, a manually operable adjustment mechanism mechanically coupled with said sliding contact of one of said two measuring resistors, indicator means for indicating the position of said last-mentioned sliding contact, an electrical adjustment mechanism with which the other of said sliding contacts is mechanically connected, the operation of said electrical adjustment mechanism being dependent upon the comparison signal delivered by said measuring bridge arrangement, switching means for selectively tapping off said comparison signal between said two measuring resistors at said fixed center taps or at said sliding contacts, further switch means for selectively conducting said comparison signal to either said electrical adjustment mechanism for said other sliding contact or to said relay means of said servo-valve means.

9. Apparatus as defined in claim 8, wherein said measuring transducer means is a differential transformer, a source of alternating-current voltage for said differential transformer, amplifier means and rectifier means for amplifying and rectifying respectively, said electrical signals delivered by said measuring transducer means before said electrical signals are supplied to said two measuring resistors.

10. Apparatus as defined in claim 8, wherein said measuring transducer means incorporates a capacitive signal transmitter means.

11. Apparatus as defined in claim 8, wherein said measuring transducer means incorporates a resistance signal transmitter means.

12. Apparatus as defined in claim 8, further including positional indicator means for indicating the position of said other sliding contact of said measuring resistor connected with said electrical adjustment mechanrsm.

13. Apparatus as defined in claim 8, including recording means provided with a recording instrument and a recording chart capable of being operably connected with said other sliding contact of said measuring resistor.

References Cited UNITED STATES PATENTS 8/1965 Plasser et al. 104-7 5/1964 Plasser et al. 1047 

